Jet-operated air compressor



M. m f v 11V 3 1,555,426 G. M KERAHAN JET OPERATED AIR COMPRESSOR Filed April 5. 1924 INVENTOR: W Z

Fatented fiept. 2-9, 1925..

insane GEORGE MCKERAHAN, OF PITTSBURGH, PENNSYLVANIA.

JET-OPERATED AIR COMPRESSOR.

' Application filed April 5,

To all whom it may concern:

Be it known that l, Gnonen Molinnarrxtn, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Jet-@perated Air Compressor. of which the following is a specification.

011 October 2nd, 1923, Letters Patent 1369,2364 were issued to the present applicant for a jet operatet. air compressor in which air filled tubular chambers are revolved across a jet of water, steam or other fluid, the motion of the wheel permitting the jet to enter successively the open ends of the air tubes and the portions of the jet thus separated acting as pistons by which the air or other gas is compressed The present invention is an improvement in the above mentioned air. compressor and its object is to provide a form of jet nozzle which will increase the effectiveness of the piston action with a corresponding large increase of the compressofls-efficiency and capacity.

The invention set forth inthe above Letters Patent shows a jet nozzle which closely conforms to the transverse dimensions, both in the direction of the wheels radius and in the circumferential direction, of each of the air chambers. In the present improve-- mentthe nozzle, in that direction which corresponds to the circumferential wicth of the air chamber, is given a width greater than a single air chamber, or equal to the circumferential width of two or more of the air chambers as may be required, as no useful effect would be gained by giving the nozzle a greater area'than the air chamber in the direction radial to the air wheel. At the same time the conformity of the nozzle with the radial depth of the air chambers remains unchanged. The improved nozzle will be especially useful for liquid jets.

In the above mentioned Letters Patent two designs of the compressor are illustrated, one in which the air wheel rotates within a closely fitting stationary casing and another design in which the casing tightly fits and revolves with the wheel. The improved nozzle is equally applicable to both designs but it will be suflicient if its application to the first named design is illustrated in this application for Letters Patent.

In the accompanying drawings, Fig. 1 shows acentral section through the air wheel casing and the two etnozzles and a full side 1924. Serial No. 704,423.

view of the air wheel within its casing. 2 shows a cross section of the two nozzles close to their discharge face. the section being taken on the line 22 of 1. Fig. 2 also shows an end view of the air wheel chambers and the wheel casing. The four diagrams, Figs. 3 to 3, illustrate the greatly superior piston obtained from my improved nozzle.

In the illustrations the stationary casing 1 is disposed vertically. By means of lugs 2 it rests upon and is secured to the two jet nozzles 3, the latter leading from the common supply pipe 4 which would connect with the pipe or the discharge end of the pump supplying the jet fluid, the pump not being shown. The chambered air wheel 5 at its upper end rotates in bearing 6 which is secured to theinterior of disciiarge tube 7 by means of radial ribsJS. The lower end of wheel 5 rotates in bearing 9 which is shown integral with the nozzles The wheel is supported by hearing collar 10 which is inclosed by oil cup 11 which affords bath lubrication for bearing and journal. The air chambers 12 of wheel 5 are formed on two sides by vanes or walls 13 which are given a close running fit within the stationary casing 1. The wheel and casing are given a slight taper thus insuring a close fit of the fluid pistons as they advance through the air chambers; this taper also allows accurate adjustment of the wheel fit within its casing by moving the wheel in the direction of its axis and adjusting collar bearing 10 to suit.

Nhen a liquid jet is used to operate the compressor the air chambers 12 are given a helical direction along the wheel as shown. whether the wheel is rotated by impact of the jet or by other means.

Discharge tube 7 would connect to a separating receiver which is not shown. If desired this tube may be lengthened to form a compression tube in which the discharge energy of the tiuid pistons would be further utilized.

By referring to Fig. 2 it is seen that each nozzle has a depth conforming to the radial depth of the air wheel chambers, but in the circumferential direction the nozzle is made equal to the width of two air chambers. This excess of nozzle width may be any quantity desired provided a sufficient area is left uncovered bythe nozzles as will freely I admit the air charges to the wheel chambers;

but a nozzle wider than two or three air chamber widths will seldom be needed.

It should be understood that the mere circumferential widening of the nozzle will not effect the object of the improvement which consists in a circumferential widening of the nozzle relative to the air chamber width and the simultaneous overlapping of more than one chamber by the nozzle as clearly shown in Fig. 2.

The nature and very great value of the re sult obtained from this improvement is clearly seen by considering Figs. 3 to 3".

These diagrams are to be regarded as enlarged sections through an air chamber and a contained fluid piston, the section being taken on the line 33 of Fig. 2. For sake of greater olearness the helical curve of walls 13 is ignored and the walls shown straight. The straight arrows show the direction of piston as propelled by the jet, and the curved arrows indicate the motion of the air chamber across the jet.

Fig. 3 shows an ideal diagram in which the piston section is a true rectangle, this form not being attainable. Fig. 3 shows a piston delivered by a nozzle having the same width as the air chamber in the circumferential direction. Line 145 is the line of admission and 15 the line of cut-off. The opposite points 16 occur when the nozzle is central with the air chamber. By increasing the jet velocity or by reducing the air wheel speed the piston is lengthened and takes the form shown at 3", in which the volume of the piston is increased but its rhomboidal deforma tion is also increased.

Fig. 3 shows the piston obtained by my improved nozzle. This piston has the same volume as 3 but the sloping lines of admission and cut-off bound only a small part of the piston, there being a full, oppositely supported body of fluid between points 17 during which period there has been a jet discharge simultaneously over the whole cross area of the air chamber.

The ideal piston shown in Fig. 3 is not possible with this machine because the jet is delivered to the air chamber progressively as the chamber enters and passes across the jet. Hence that part of the jet which first enters the air chamber has travelled some distance within the chamber by the time the whole of the air chamber has moved before the jet. The result is that the forward face of the piston slopes at an acute angle with the pistons direction of travel as shown by admission lines 14 of the diagrams 3 3 and 3.

Where the nozzle, in the circumferential direction, has the same width as the air chamber cut-off begins at the same moment when full admission is reached, that is, when the air chamber has moved into central alignmentwith the nozzle; this stage is indicated by points 16 of Figs. 3 and 3 As the time required for the air chamber to pass out of the jet is the same as that required for its progressive entrance the rear end of the piston also slopes at a like acute angle with the pistons direction of travel as shown by lines of cut-01f 15 of the diagrams, the extreme rear part of the pistons indicating the stage when the air chamber is finally passing out of the jet.

In diagrams 3 and 8 the piston has great over-all length in the direction of its travel. But since fluid pressure acts perpendicularly to the exposed surface it follows that the effective piston action is limited by the distance near points 16 when measured perpendicularly to the sloping lines of admission and cut-off l4 and 15; the long triangular parts at front and rear of pistons 3 and 3 are almost useless for compression because the air pressure will break through the piston-fluid perpendicularly near points 16.

If the jet nozzle is made considerably wider than the air chamber in the circumferential direction, that is, in the direction of the chambers travel, then cut-off will not begin at the moment when the air chamber is receiving a full charge from the jet, the moment of full admission, but instead, the period is prolonged during which the air chamber is receiving simultaneously a piston-charge over its whole cross area and consequently the point where full admission is reached and the point where cut-off begins are separated by some distance when measured parallel with the pistons direction of travel as shown by points 17 of Fig. 3, this diagram showing a piston delivered by my improved nozzle. Air pressure acting perpendicularly against face 14 of 3 has nearly the whole length of the piston opposed to it as contrasted with the short perpendicular distance near points 16 of 3 the latter piston having equal volume with 3.

Since increasing the circumferential width of the nozzle over that of the air chamber increases the duration of jet discharge to each chamber, and since increasing the air chamber speed reduces the duration of jet discharge to each chamber it follows that in pistons of equal volume as 3 and 3, the piston 3 delivered by my improved nozzle is obtained at a higher air chamber speed than 3*.

The improved action of my new nozzle is therefore twofold; it prolongs the period during which the air chamber receives a piston of full cross area as seen between points 17 of Fig. r and also by permitting a higher air chamber speed the triangular and almost useless parts on the front and rear of the piston are very much shortened, the latter effect resulting from the fact that the higher air chamber speed reduces the time interval between the beginning of admission and full admission and the time interval between the beginning and completion of cut-off. This shortening of the faces 1% and 15 is seen in Fig. 3". Thus the piston delivered by the improved nozzle approaches somewhat the ideal piston shown in Fig 3 with a large increase of compressive effect as already explained.

Diagram S and the improved nozzle diagram 3 are not to be regarded as having their points of divergence exaggerated for the sake of clearness and emphasis; they may be taken as accurate theoretical diagrams for the combination of jet velocity and air chamber speed which they represent and they are similarly valid for any other combination.

It is important to explain that in this specification by the circumferential width of the air chamber is meant the true width as measured perpendicularly to the walls 13, Fig. 1, and not the sloping width as measured on the face of the wheel parallel with the direction of rotation. The difference be tween these two dimensions is only small when small angle of helix is used for the air chambers. But where the air chamber speed may require a large angle and short lead of helix the difference will be considerable and it may happen that a circumferential width of jet nozzle which provides a sufficient excess over the air chambers true width, as above defined, may yet be no more than the air chambers sloping width when measured at the wheel face on the plane of rotation; but this condition will not impair the superior form of piston delivered by this improved nozzle.

The drawings show two jet nozz es but a single nozzle or more than two may be used as required.

Equipped with this improved nozzle the compressor may be used as vacuum pump or e-Xhauster by n'iaking the required connections.

hat I claim as new is:

l. In a jet operated air compressor, tubu lar air chambers disposed lengthwise about a central shaft on which the wheel is rotated;

one or more jet nozzles disposed in alignment with, and conforming to, the radial depth of said air chambers in the direction of the wheeis radius, each of said nozzles having a width, in the direction of the wheels circumference, greater than the width, in a circumferential direction, of one air chamber; and means at the opposite end of the wheel for receiving the discharge from the wheel chambers.

2. in a jet operated air compressor, tubular air chambers disposed helically about a central shaft on which the wheel is rotated; one or more jet nozzles disposed in alignment with, and conforming to, the radial depth of said air chambers in the direction of the wheels radius, each of said nozzles having a width, in the direction of the wheels circumference, greater than the width, in a circun'iferential direction of one air chamber; and means at the opposite end of the wheel forv receiving the discharge from the wheel chambers.

3. In a jet operated air compressor, tubu lar air chambers disposed lengthwise about a central shaft on which the wheel is rotated; one or more jet nozzles disposed so that the open ends of the revolving air chambers shall successively come into alignment with the nozzles; each of said nozzles having a cross area greater than the cross area of a single air chamber, and means at the opposite end of the air chamber wheel for receiv ing the discharge from the wheel chambers.

4e In a jet operated air compressor, tub-1r lar air chambers disposed helically about a central shaft on which the wheel is rotated; one or more jet nozzles disposed so that the open ends of the revolving air chambers shall successively come into alignment with the nozzles; each of said nozzles having a cross area greater than the cross area of a single air chamber; and means at the opposite nd of the air chamber wheel for receiving the discharge from the wheel chambers.

GEORGE MoKERAI-IAN. 

